CN108291639B - Electromechanical system for controlling the operating modes of a selectable clutch assembly - Google Patents

Abstract

The invention provides an electromechanical system for controlling the operating mode of a selectable clutch assembly and an overrunning coupling and electromechanical control assembly using the same. A bi-directional, electrically driven actuation assembly including an output member is connected to the control member for selective, small-displacement angular rotation of the control member about the first axis between different angular positions corresponding to different operating modes of the clutch assembly. The actuation assembly includes a rotating output shaft, a threaded screw shaft connected to the output shaft for rotation about a second axis substantially perpendicular to the first axis, and a cam having a contoured surface. The cam is screwed to the screw shaft to linearly move along the second axis when the screw shaft is rotationally moved. The output member rides on a contoured surface of the cam such that the output member rotates with the control member about the first axis.

Description

Electromechanical system for controlling the operating modes of a selectable clutch assembly

Cross Reference to Related Applications

This application is a continuation-in-part application of U.S. application No. 14/933,345 filed on 5/11/2015, which in turn claims priority to U.S. provisional application No. 62/076,646 filed on 7/11/2014. This application also claims priority from U.S. provisional application No. 62/259,713 filed on 25/11/2015.

Technical Field

At least one embodiment of the present invention relates generally to systems for controlling the operating mode of a clutchable assembly, and more particularly to electromechanical systems for controlling the operating mode of such assemblies.

Background

A typical one-way clutch (i.e., OWC) includes a first connecting member, a second connecting member, and a first set of locking members located between opposing surfaces of the two connecting members. One-way clutches are designed to lock in one direction and allow free rotation in the opposite direction. Two types of one-way clutches often used in vehicular, automatic transmissions include:

a roller type comprising spring-loaded rollers located between the inner and outer races of the one-way clutch (roller type is also used without springs on some applications); and

a sprag type comprising an asymmetrically shaped sprag located between an inner race and an outer race of a one-way clutch.

The one-way clutch is typically overrunning during engine braking rather than effecting engine braking. It is for this reason that there is a friction pack at the same drive node. An optional dynamic clutch may be used to prevent overrunning operating conditions and to effect engine braking.

The controllable or selectable one-way clutch (i.e., OWC) is different from conventional one-way clutch designs. Alternative OWCs often incorporate a second set of struts or locking members in combination with a slide plate. This additional set of locking members plus slide plates adds a number of functions to the OWC. Controllable OWCs are capable of producing a mechanical connection between a rotating or stationary shaft in one or two directions, as required by the design. Furthermore, OWCs can overrun in one or both directions depending on the design. The controllable OWCs contain externally controlled selection or actuation mechanisms. The movement of the selection mechanism may be between two or more positions corresponding to different modes of operation. The selection mechanism is a separate system or assembly that is fixed relative to the OWC by the same fastening technique. Such selection mechanisms are fixed in a separate and subsequent operation after the OWC is formed. This subsequent operation, whether automated or otherwise, requires an additional work station, which increases, among other things, the manufacturing time and cost of the finished assembly.

In addition, the fact that separate external components may be mounted on or near the OWC is a source of quality defects and therefore increases the cost of manufacturing such a controllable or alternative OWC, which is significant on a mass production basis. Furthermore, due to dimensional stacking issues, control element or option board adhesion may occur, especially during long term use.

Driven by the ever-increasing demand by industry, government regulatory agencies and consumers for durable and inexpensive products that function equivalently or better than prior art products, there remains a need for improved clutches that withstand difficult conditions of use, such as extreme temperatures. This is particularly true in the automotive industry where developers and manufacturers of clutches for automotive applications must meet many competing performance specifications for these articles.

Another problem associated with prior art linkage and control assemblies is that it is undesirable to have a large distance between the control element and the actuator that moves the control element. A larger distance reduces the amount of available space for positioning the components. For example, in vehicles, the amount of space for such components is often very limited.

U.S. patent No. 5,927,455 discloses a bi-directional overrunning pawl clutch. Us patent No. 6,244,965 discloses a planar overrunning coupler for torque transmission. U.S. patent No. 6,290,044 discloses a selectable one-way clutch assembly for an automatic transmission. Us patent No. 7,258,214 discloses an override connection assembly. Us patent No. 7,344,010 discloses an override connection assembly. U.S. patent No. 7,484,605 discloses an overrunning radial coupling assembly or clutch.

Other related U.S. patent publications include 2012/0145506, 2011/0192697, 2011/0183806, 2010/0252384, 2009/0194381, 2008/0223681, 2008/0169165, 2008/0169166, 2008/0185253, and the following U.S. patent numbers 8,079,453, 7,992,695, 8,051,959, 7,766,790, 7,743,678, and 7,491,151.

U.S. patent No. 8,272,488 discloses in its fig. 9a-9C (labeled as fig. 1A-1C, respectively in the present application) a "vertically actuated shift valve" lockout mechanism, generally designated 500. A control plate or element 502 of a one-way clutch is provided that moves or slides in a displacement direction between a groove plate and a recess plate (not shown) of the clutch to controllably cover and uncover spring-biased posts 504 in the groove plate. During sliding movement of the valve or piston, generally indicated at 512, within a bore 513 formed in the housing 514, the free end 506 of the actuator arm or actuator pin, generally indicated at 508, may move in a direction substantially perpendicular to the direction of displacement of the control plate 502 within a curved pin recess or groove 510 formed in an outer surface 528 of the valve or piston 512. As shown in fig. 1A, the side walls or surfaces of the groove 510 lock the pin 508 therebetween to prevent the pin 508 from moving in a direction parallel to the direction of displacement of the control plate 502. The groove 510 may be curved and the free end 506 of the actuator arm 508 may move within the groove 510 in both a direction substantially parallel to the displacement axis and a direction substantially perpendicular to the displacement axis during movement of the piston 512 within the housing 514. A compression spring 516, also disposed within the bore 513, is biased between a cap 518 of the housing 514 and an end 520 of the valve 512. The plate 502 of the one-way clutch is disclosed in fig. 1A as being in its overrunning position and is moved to its locked position in fig. 1C. As shown in fig. 1B and 1C, application of a control pressure 522 at an opposite end 524 of the valve or piston 512 by a control portion 523 of the housing 514 causes the valve 512 to move against the bias of the compression spring 516 such that an actuation pin 508 secured to the control plate 502 at a pin attachment portion 526 moves within a curved pin recess or groove 510 formed in an outer surface 528 of the valve 512. As shown in FIG. 1C, one of the struts 504 now extends through an aperture 530 formed in the control plate 502 to lock the one-way clutch.

Other U.S. patent publications disclosing controllable or selectable one-way clutches include U.S. patent nos. 6,193,038, 7,198,587, 7,275,628, 8,602,187, and 7,464,801, and U.S. published application nos. 2007/0278061, 2008/0110715, 2009/0159391, 2009/0211863, 2010/0230226, and 2014/0190785.

Nevertheless, there remains a need to provide disengagement of non-hydraulic clutches under load, particularly during extremely low start temperatures (i.e., -40 degrees Fahrenheit or less), while conserving space in the automatic transmission environment.

Other U.S. patent documents relevant to the present application include: 2,947,537, 2,959,062, 4,050,560, 4,340,133, 4,651,847, 6,607,292, 6,905,009, 7,942,781, 8,061,496, 8,286,772, 2004/0238306, 2006/0185957, 2007/0034470, 2009/0255773, 2010/0022342, 2010/0255954, 2011/0177900, 2012/0090952, 2012/0152683 and 2012/0152687.

As used herein, the term "sensor" is used to describe a circuit or assembly that includes a sensing element and other components. In particular, as used herein, the term "magnetic field sensor" is used to describe a circuit or assembly that includes a magnetic field sensing element and electronics connected to the magnetic field sensing element.

As used herein, the term "magnetic field sensing element" is used to describe various electronic elements capable of sensing a magnetic field. The magnetic field sensing element may be, but is not limited to, a hall effect element, a magnetoresistive element, or a magnetotransistor. It is well known that there are different types of hall effect elements, such as planar hall elements, vertical hall elements, and Circular Vertical Hall (CVH) elements. Different types of magnetoresistive elements are also known, such as Giant Magnetoresistive (GMR) elements, Anisotropic Magnetoresistive (AMR) elements, Tunneling Magnetoresistive (TMR) elements, indium antimonide (InSb) sensors and Magnetic Tunnel Junctions (MTJ).

It is well known that some of the above-mentioned magnetic field sensing elements tend to have their axis of maximum sensitivity parallel to the substrate supporting the magnetic field sensing elements, and others of the above-mentioned magnetic field sensing elements tend to have their axis of maximum sensitivity perpendicular to the substrate supporting the magnetic field sensing elements. In particular, planar hall elements tend to have a sensitivity axis perpendicular to the substrate, while magnetoresistive elements and vertical hall elements (including Circular Vertical Hall (CVH) sensing elements) tend to have a sensitivity axis parallel to the substrate.

Magnetic field sensors are used in a variety of applications, including but not limited to angle sensors that sense the angle of direction of a magnetic field, current sensors that sense the magnetic field generated by current carried by a charged conductor, magnetic switches that sense the proximity of a ferromagnetic object, rotation detectors that sense the passing ferromagnetic objects (e.g., the magnetic domains of a ring magnet), and magnetic field sensors that sense the magnetic field density of a magnetic field.

Modern motor vehicles use engine drive systems with gears of different sizes to transfer power generated by the vehicle engine to the wheels based on the speed at which the vehicle is traveling. The engine drive train typically includes a clutch mechanism that can engage and disengage the gears. The clutch mechanism may be operated manually by the driver of the vehicle or automatically by the vehicle itself based on the speed at which the driver wishes the vehicle to operate.

In an automatically shifting vehicle, it is desirable for the vehicle to sense the position of the clutch for smooth, efficient shifting between the gears of the transmission and for overall efficient transmission control. Thus, a clutch position sensing component for sensing the linear position of the clutch may be used by an automatic transmission vehicle to assist in gear shifting and transmission control.

Current clutch position sensing components use magnetic sensors. One advantage of using a magnetic sensor is that the sensor does not need to be in physical contact with the object being sensed, thereby avoiding mechanical wear between the sensor and the object. However, when the sensor is not in physical contact with the object being sensed, the actual linear clutch measurement accuracy may suffer due to the necessary clearance or tolerance between the sensor and the object. Furthermore, current sensing systems that address this problem use coils and some dedicated integrated circuits that are relatively expensive.

Us patent No. 8,324,890 discloses a drive clutch position sensor that includes two hall sensors located at opposite ends of a flux concentrator outside the housing of the transmission to sense the magnetic field generated by a magnet attached to the clutch piston. To reduce sensitivity to magnet-to-sensor clearance tolerances, the ratio of the voltage of one hall sensor to the sum of the voltages of two hall sensors is used to correlate with piston position, and thus clutch position.

For purposes of this application, the term "coupling" should be understood to include a clutch or brake wherein one plate is drivably connected to a torque-transmitting element of the transmission and the other plate is drivably connected to the other torque-transmitting element or is anchored and held stationary relative to the transmission housing. The terms "coupler", "clutch" and "brake" are used interchangeably.

Disclosure of Invention

It is an object of at least one embodiment of the present invention to provide a non-hydraulic electromechanical system and an override connection and control assembly using the same in which rotational motion about a first axis is converted to linear motion which is in turn converted by camming action back to rotational motion about a second axis substantially perpendicular to the first axis.

In carrying out the above object and other objects of at least one embodiment of the present invention, an electromechanical system for controlling an operating mode of a clutchable assembly is provided. The system includes a control member mounted for controlled rotation about a first axis and a bi-directional, electrically-driven actuation assembly including an output member connected to the control member for selective, small-displacement angular rotation of the control member about the first axis between different angular positions corresponding to different operating modes of the clutch assembly. The actuation assembly includes a rotating output shaft, a threaded screw shaft connected to the output shaft for rotation about a second axis substantially perpendicular to the first axis, and a cam having a contoured surface. The cam is screwed to the screw shaft to linearly move along the second axis when the screw shaft is rotationally moved. The output member rides on a contoured surface of the cam such that the output member rotates with the control member about the first axis. The system also includes control logic for determining a desired operating mode of the clutch assembly and generating a corresponding position command signal, and an actuation controller for controllably supplying electrical power to the actuation assembly to move the control member to a desired angular position based on the position command signal.

The actuator controller may receive position command signals from a remote electronic control unit via the bus.

The electronic control unit may be a transmission electronic control unit of a vehicle, and the bus may be an on-board bus.

The actuation assembly may include a dc motor having an output shaft for driving the control member.

The actuation controller may include a current sensor for monitoring the motor current. The control logic may control the dc motor based on the motor current.

The actuation assembly may include at least one non-contact position sensor for providing a position feedback signal that varies with the position of the cam along the second axis. The control logic may control the dc motor based on the position feedback signal.

Each sensor may include at least one magnetic or ferromagnetic magnet mounted for movement with the cam and at least one magnetic field sensing element disposed adjacent to and stationary relative to the at least one magnet to sense magnetic flux to generate a position feedback signal.

Each magnetic field sensing element may be a hall effect sensor.

The cam may be back-drivable on the screw shaft. The system may further include a return biasing member for applying a biasing force to the cam when the actuating assembly is de-energized, thereby returning the cam to a position on the screw shaft corresponding to the safe clutching mode.

The cam may not be back-drivable on the screw shaft.

The system may further include a lockout mechanism for preventing the cam from moving linearly on the screw shaft.

The latching mechanism may comprise a latching solenoid.

The output member may comprise an actuating pin or arm connected to the control member.

The contoured surface may be defined by a groove in which the free end of the output member is received and retained.

The groove may have end portions that may provide anti-backlash features and an intermediate portion between the end portions.

The control member may be a control plate or a selector plate rotatable about a first axis.

The control member may have at least one opening extending completely through the control member.

The controller may include a boost circuit for enabling the controller to provide greater power to the actuation assembly than the rated input power typically available from the vehicle's battery to increase the output torque and speed of the actuation assembly.

The boost circuit may also be used as an energy storage device to actuate the clutch in the event of a loss of battery power (i.e., 12 volt power) to the vehicle, which may be used as a fail-safe mechanism for a mechanical lockout design.

Further, in carrying out the above objects and other objects of at least one embodiment of the present invention, an override connection and electromechanical control assembly are provided. The assembly includes a connection subassembly including first and second connection members each having first and second connection faces closely opposed to each other, at least one of the first and second connection members being mounted for rotation about a first axis. The assembly further includes a control member mounted for controlled rotation about the first axis between the first and second connection faces, and a bi-directional, electrically driven actuation assembly including an output member connected to the control member for selective, small-displacement angular rotation of the control member about the first axis between different angular positions corresponding to different operating modes of the connection subassembly. The actuation subassembly includes a rotating output shaft, a threaded screw shaft connected to the output shaft for rotation about a second axis substantially perpendicular to the first axis, and a cam having a contoured surface. The cam is screwed to the screw shaft to linearly move along the second axis when the screw shaft is rotationally moved. The output member rides on a contoured surface of the cam such that the output member rotates with the control member about the first axis. The assembly also includes control logic for determining a desired operating mode of the connection subassembly and generating a corresponding position command signal. An actuation controller controllably supplies power to the actuation subassembly to move the control member to a desired angular position based on the position command signal.

The actuator controller may receive position command signals from a remote electronic control unit via the bus.

The electronic control unit may be a transmission electronic control unit of a vehicle, and the bus may be an on-board bus.

The actuation subassembly may include a dc motor having an output shaft for driving the control member.

The actuation controller may include a current sensor for monitoring motor current, and the control logic may control the dc motor based on the motor current.

The actuation sub-assembly may include at least one non-contact position sensor for providing a position feedback signal that varies with the position of the cam along the second axis. The control logic may control the dc motor based on the position feedback signal.

Each sensor may include at least one magnetic or ferromagnetic magnet mounted for movement with the cam and at least one magnetic field sensing element disposed adjacent to and stationary relative to the at least one magnet to sense magnetic flux to generate a position feedback signal.

Each magnetic field sensing element may be a hall effect sensor.

The cam may be back-drivable on the screw shaft, and the assembly may further include a return biasing member for applying a biasing force to the cam upon de-energization of the actuation subassembly to return the cam to a position on the screw shaft corresponding to the safe connection mode.

The cam may not be back-drivable on the screw shaft.

The assembly may further include a latching mechanism for preventing the cam from moving linearly on the screw shaft.

The latching mechanism may comprise a latching solenoid.

The output member may comprise an actuating pin or arm connected to the control member.

The contoured surface may be defined by a groove in which the free end of the output member is received and retained.

The groove may have end portions and an intermediate portion between the end portions. The end portions may provide anti-backlash features.

The control member may be a control plate or a selector plate rotatable about a first axis.

The assembly may further comprise a locking member disposed between the first and second coupling faces of the coupling member. The locking member is movable between a first position and a second position. The control member may be operable to control the position of the locking member.

The locking member may be a counter strut.

The control member may have at least one opening extending completely through the control member for allowing the locking member to extend through the opening to the first position of the locking member in the control position of the control member.

The controller may include a boost circuit for enabling the controller to provide greater power to the actuation sub-assembly than the rated input power typically available from the vehicle's battery to increase the output torque and speed of the actuation sub-assembly.

The boost circuit may also be used as an energy storage device to actuate the clutch in the event of a loss of battery power (i.e., 12 volt power) to the vehicle, which may be used as a fail-safe mechanism for a mechanical lockout design.

One of the connection members may include a notch plate, and the other of the connection members may include a groove plate.

While exemplary embodiments are described above, these embodiments are not intended to describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various embodiments may be combined to form additional embodiments of the invention.

Drawings

Fig. 1A to 1C are partially sectioned diagrammatic views of a prior art control member or element in the form of an actuating shift valve or piston (blocking mechanism) together with an associated strut and its control device, in different control positions in different views.

FIG. 2 is an exploded perspective view of an overrunning coupling or clutch assembly constructed in accordance with at least one embodiment of the present invention;

FIG. 3 is a schematic diagram of motor operating point trigonometric coordinates illustrating the interrelationship of electric motor output speed, power consumption and output torque;

FIG. 4 is a schematic view of a nut or cam threaded onto a lead screw or screw shaft and showing an enlarged cam groove profile or contour surface having a pair of "rest points" at opposite ends of the groove;

FIG. 5 is a view, partially in cross-section, of a pair of screw shafts, one having a steep (small) lead angle and the other having a larger lead angle;

FIG. 6 is a top plan view, partially in cross-section, of a first embodiment of components of an electromechanical system for controlling the operating mode or state of a clutchable assembly, generally of the type shown in FIG. 2;

FIG. 7 is a top plan view, partially in cross-section, of a second embodiment of a component of the system;

FIG. 8 is a top plan view, partially in cross-section, of a third embodiment of a component of the system;

FIG. 9 is a schematic block diagram of a motor controller having a fail-safe boost power supply circuit in communication with a transmission controller via a CAN interface;

FIG. 10 is a detailed circuit diagram of the current fail-safe power supply circuit of FIG. 9;

FIG. 11 is a view similar to that of FIG. 9, but showing a relatively simple controller for the actuating assembly capable of back-driving, showing PWM and direction command outputs from the transmission controller;

FIG. 12 is a view similar to that of FIG. 11 but showing a boost circuit in the actuation controller capable of back driving;

FIG. 13 is a block diagram of a TECU, power switch and supply circuitry, a motor, and one or more sensors, where the TECU directly controls the direction of the motor and monitors the position of the actuator through Hall effect sensors while indirectly powering the motor; and

fig. 14 is a schematic block diagram of a controller power stage similar to fig. 13 including a high side switch and a reverse polarity switch, fig. 14 showing an alternative control method where an external TECU controls the actuator through the circuit of fig. 14, fig. 13 showing a relay based cost effective approach, fig. 14 showing a solid state implementation that can be more efficiently integrated into the power control module or external actuation control circuit board.

Detailed Description

As required, detailed embodiments of the present invention are disclosed herein, however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The drawings are not necessarily to scale, and some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

Referring again to the drawings, FIG. 2 is an exploded perspective view of an overrunning clutching or connection assembly, generally indicated at 10, constructed in accordance with at least one embodiment of the present invention. However, it should be understood that the present invention may be used with a variety of selectable clutches, such as clutches having three or more operating modes or states. In fact, the present invention can be used with Controllable Mechanical Diodes (CMD) having an infinite number of operating modes or mechanical states.

As described in U.S. patent No. 8,602,187 and published U.S. patent application No. 2014/0190785, which are assigned to the assignee of the present application, the assembly 10 includes an annular inverted channel plate or first outer connecting member, generally designated by the reference numeral 12. An axially extending outer surface 14 of the plate 12 has external splines 16 for connecting the plate 12 to an inner surface of a transmission housing (not shown). The radially extending inner surface or attachment face 18 of the plate 12 is formed with spaced apart slots 20, with opposed legs 22 being pivotally biased outwardly by coil springs (not shown) disposed in the slots 20 below their respective legs 22. Preferably, twelve counter struts 22 are provided. However, it should be understood that more or fewer opposing struts 22 may be provided.

The assembly 10 further includes a control member or element, generally designated 26, in the form of a selector slide plate having a plurality of spaced apertures 28 extending completely therethrough to permit the reversing struts 22 to pivot in their slots 20 and extend through the apertures 28 to engage spaced locking structures or angled reversing notches (not shown) formed on the radially extending surfaces or connecting faces of the forward or inner slot plates or connecting members when the plates 26 are properly angularly positioned about the common first central axis of rotation 36 by an output member in the form of an actuating pin or arm 38. The pin 38 is connected or fixed to the plate 26 for movement therewith.

As shown in U.S. patent No. 8,602,187, the pin 38 may extend through a notch or elongated slot formed by a wall or wall portion of the peripheral end wall of the plate 12. The wall may be a common wall separating the first connection member 12 and the housing of the control system and being shared by the first connection member 12 and the housing of the control system. An elongate slot may extend between and thereby communicate the inner surface of the housing and the inner surface of the wall of the first connection member 12. The pin 38 is movable in the slot between different use positions to slide or displace the plate 26 between its control positions to alternately cover or uncover the support post 22 (i.e., to engage or disengage, respectively, the opposing support post 22).

The plate 34 includes a splined ring having internal splines 46 formed at an axially extending inner surface 48 thereof. The radially extending surface 50 or a connection surface spaced from another connection surface (not shown) of the plate 34 has a plurality of spaced apart slots 52 formed therein to receive a plurality of forward struts 54 therein, the plurality of forward struts 54 being pivotally biased by corresponding coil springs (not shown). Preferably, fourteen forward struts 54 are provided. However, it should be understood that more or fewer forward struts 54 may be provided.

The assembly 10 may also include a second outer connecting member or notch plate, generally indicated at 58, having a plurality of locking structures, cams or notches (not shown) formed in a radially extending surface or connecting surface (not shown) thereof by which the forward strut 54 locks the front plate 34 to the notch plate 58 in one direction about the axis 36, but allows free rotation thereof in the opposite direction about the axis 36. The notch plate 58 includes external splines 64 formed on an axially outer surface 66 of the plate 58 and received and retained within axially extending recesses 68 formed in the axially extending inner surface 47 of the outer peripheral end wall of the plate 12.

The assembly 10 may also include a snap ring, generally indicated at 72, having an end 74 and fitting within an annular groove 76 formed in the inner surface 47 of the end wall of the plate 12 to hold the plates 12, 26, 34 and 58 together and limit axial movement of the plates relative to each other.

The pin 38 has a control position for disengaging the counter stay 22. In one embodiment, the pin 38 is rotated about the axis 36 in a forward over-travel direction by about 7 ° to rotate the selector plate 26, which in turn allows the reverse struts 22 to move from their disengaged position in their slots 20 to a position where they engage with notches (not shown) of the plate 34.

In the three disclosed embodiments, the components of the electromechanical system used to control the operating mode or state of the sowc assembly 10 are designated by reference numerals 80, 80' and 80 "in fig. 6,7 and 8, respectively, wherein the components of the second embodiment that perform the same or similar functions as the components of the first embodiment have the same reference numerals but with a single prime symbol, and wherein the components of the third embodiment that perform the same or similar functions as the components of the first two embodiments have the same reference numerals but with a double prime symbol.

The components of the first embodiment system 80 (i.e., fig. 6) include a bi-directionally electrically driven actuation assembly, generally indicated at 82, connected to the control member or control plate 26 for selective, small-displacement movement of the control member or control plate between first and second positions corresponding to the first and second operating modes of the clutch assembly 10, respectively. As mentioned before, more than two positions may be provided, for example three positions of the tri-state CMD. In fact, at least theoretically, infinite states can be supported.

After power to the actuation assembly 82 has been purposefully terminated, the actuation assembly 82 maintains the control member 26 in the desired control position. In the first embodiment of fig. 6, the latching mechanism of the assembly 82 may comprise a self-locking threaded screw shaft, generally designated 84, connected to the output shaft of a bi-directional dc motor or brushed dc motor 88. The screw shaft rotates about a second axis 89 that is substantially perpendicular to the first axis 36.

The lead screw 84 provides high torque multiplication while still being packaged in a usable housing. The lead screw actuation assembly 82 is packaged as a retrofit into existing spaces for other actuator designs (see fig. 1A-1C). The lead screw actuation assembly 82 is similarly arranged to a hydraulically actuated valve. The added mechanical advantage of the lead screw 84 presents several advantages over the direct actuation method:

i. specifically, by selecting a sufficiently steep (small) lead angle (i.e., the lower half of fig. 5), the system 80 can be made incapable of back driving. The inability to back drive is defined as the nut 94 being unable to move by an external force acting on the nut 94. The nut 94 can only be moved by rotation of the lead screw 84. This enables a latching actuator design.

The increased torque multiplication of the lead screw 84 may allow for a reduction in the size and cost of the brushed dc drive motor 88. Fig. 3 shows the motor operating point triangular coordinates. The idea of working triangular coordinates is that it is difficult for a dc brushed motor to simultaneously satisfy high output speed, high output torque, and low power consumption. In order to meet OEM requirements for lower drive time (high motor output speed) and power consumption, the required motor output torque needs to be sacrificed or reduced. The lead screw 84 provides a higher torque multiplication ratio than other simple gear reduction devices, thereby reducing the required output torque of the motor. At lower torque requirements, a smaller dc motor may be selected. Smaller motors generally provide higher output speeds and lower power consumption required by OEMs.

In the first embodiment of fig. 6, the actuation assembly 82 includes an output member in the form of an actuation arm or pin 38. The screw shaft 84 is supported for rotational movement by a bushing 86. A thrust washer 92 is provided at one end of the screw shaft 84 to absorb thrust load.

The assembly 82 also includes a nut or cam, generally indicated at 94. The cam 94 has a contoured surface (not shown in fig. 6 for simplicity, but indicated by reference numeral 95 in fig. 4). The cam 94 is threaded onto the screw shaft 84 to move linearly along the second axis 89 upon rotational movement of the screw shaft 84. The output member or arm 38 rides on a contoured surface 95 of the cam 94 such that the output member or arm 38 rotates with the control member 26 about the first axis 36.

As shown in fig. 4, the cam surface 95 is preferably defined by a groove 96 having opposite ends 97 and an intermediate portion 99 between the opposite ends 97. End 97 provides a "stop point" at the end of cam groove 96.

In other words, lead screw nut 94 includes a cam groove 96 for engaging nut 94 with actuation arm 38. The groove 96 captures the actuator arm 38, translating linear movement of the nut 94 into planar rotational movement of the arm 38 and selector plate 26. In addition, the geometry of groove 96 creates two "rest points" for actuator arm 38. Each "rest point" is included such that internal forces of the clutch assembly on selector plate 26 and actuator arm 38 cannot cause actuator arm 38 to inadvertently move within groove 96 causing lead screw nut 94 to move linearly. This is particularly important in failsafe applications where the lead screw nut 94 can be back driven. The "rest points" at either end of the cam 94 prevent the internal forces of the clutch assembly from causing an unintended change in the mode or state of the clutch assembly.

The addition of the worm cam groove 96 of the lead screw nut makes the actuator system very insensitive to looseness between the lead screw 84 and the nut 94. With the actuating arm 38 at the "rest points" at either end of the nut's grooved profile 96, the arm 38 is less sensitive to small amounts of linear movement of the nut 94. As a result, the expensive anti-backlash feature may be eliminated from the lead screw 84 and nut or cam 94.

The actuating assembly 82 also preferably includes at least one non-contact position sensor for providing a position feedback signal that varies with the position of the cam 94. Each sensor may include at least one magnetic or ferromagnetic magnet (not shown) mounted for movement with the cam 94 and at least one, and preferably two magnetic field sensing elements 98 disposed adjacent to and stationary relative to the at least one magnet to sense magnetic flux to provide a position feedback signal to the controller (fig. 9, 11 and 12). Each magnetic field sensing element 98 is preferably a hall effect sensor. Alternatively, the sensor may comprise an inductive position sensor. The two digital sensors may be replaced by a single analog sensor or by monitoring the current drawn by the motor 88 by means of a current sensor (see fig. 11).

Since the nut 94 of fig. 6 is not back-drivable (provides a locking function), there is typically no need for any separate locking device.

In the second embodiment of fig. 7, the lead angle of the screw is increased (i.e., the upper half of fig. 5) so that the nut 94 'can be back driven, and a return spring 101' is added to return the nut 94 'to a safe clutching state or mode when the motor 88' is de-energized. The characteristics are as follows:

-adding a passive mechanical fail-safe function;

allowing the user to remove motor power when the clutch torque is locked, allowing the selector plate 26' to partially return against the locked strut. Thus, the response time of the clutch is improved upon return to the safe (strut covered) state.

Directional control of the motor 88 'is not required since the system returns to the "post covered" condition against the energy stored in the compressed return spring 101'. This greatly simplifies the motor controller, eliminates potential failure modes and reduces control costs.

Fig. 11 shows a simple solid-state switch form for such a motor controller capable of back-driving:

1. including high side protection to prevent accidental actuation during line shorts;

2. for cost reasons, electromechanical relays may be used in place of the solid-state semiconductor devices shown therein in implementations.

The "boost" version of the motor controller of fig. 11 is shown in fig. 12. As shown therein, a transmission controller (TECU) applies a time-varying pulse width modulated control signal to a motor controller. Based on the duty cycle of the control signal, the motor controller enters a boost mode or supplies pulse width modulated power to the dc motor 88'.

The controller of fig. 12 may determine (i.e., via motor current and/or sensor feedback) whether the clutch is torque-locked. The controller may then decide to activate the boost circuit and utilize the energy stored by the storage capacitor to deliver high power to the motor in an attempt to disengage the clutch. It should be understood that the ability to utilize boosted power is not limited by the controller of fig. 12, but may also be implemented in the controller of fig. 9.

The advantages of the embodiment of fig. 12 are numerous. The output speed and torque of the brushed dc motor is a function of the applied power. It is generally safe to briefly exceed the rated input power of the motor 88 if power is applied in steps. Applying higher input power results in higher motor output speed and torque. For low temperature conditions, there may be increased resistance between the selector plate 26 and the housing due to the presence of cold, high viscosity automatic transmission fluid. To transmit the increased torque required to free the selector plate 26 from the viscous oil, a higher than usual amount of power is transmitted to the motor 88 for a limited time. The boost circuit of fig. 12 generates and stores the higher voltage energy required to free the select plate. Under normal temperature conditions, the boost circuit is bypassed to improve system efficiency. The boost circuit also has the advantage of limiting the instantaneous power drawn from the vehicle battery, which is important because the voltage level of the battery may be lower than usual due to low temperatures.

In the third embodiment of fig. 8 (which is similar to the second embodiment), a latching mechanism in the form of a latching solenoid 110 "is provided substantially perpendicular to the cam 94", which latches the cam 94 "in either clutch mode or state.

Preferably, the latching solenoid 110 "is push-type and spring-return, such that the armature of the solenoid 110" retracts when de-energized, allowing the cam's return spring 101 "to return the clutch to a safe state. The advantage of using solenoid 110 "is that it reduces power consumption (return solenoid as opposed to lead screw motor) and prevents accidental actuation in either clutch state.

Referring to fig. 12, the motor controller shown therein implements a failsafe by adding a capacitive backup power source and a separate controller. Referring to fig. 9 and 10, the circuits shown therein:

-providing an electrical based fail-safe capability; and

-allowing a voltage level higher than the battery potential to be applied to the motor for a short time to increase the actuation force.

In summary, the electric motor 88 "rotates the lead screw or screw shaft 84", which lead screw or screw shaft 84 "converts the rotational motion of the motor into linear motion of the nut. Nut 94 "has a contoured surface defined by a groove 96, which groove 96 retains captive actuator arm 38", translating linear movement of the nut into rotational movement of actuator arm 38 "of the selector plate. A bushing 86 "mounted at the end of the lead screw 84" allows the lead screw 84 "to rotate with low loss. In the event of excessive plate force selection, the thrust washer 92 "absorbs the thrust load.

The vehicle's Transmission Electronic Control Unit (TECU) provides and regulates power for driving the motor 88, 88' or 88 ". The control circuit of fig. 9-14 may be connected to the motor 88, 88' or 88 "to enable bi-directional control of the motor. In some embodiments, the TECU determines the direction in which to drive the motor, sets the digital output accordingly, and then activates its VFS (variable force solenoid) output to drive the motor. Traditionally, existing TECUs employ variable force solenoid control to operate the hydraulic control circuit of the transmission to change the clutch state. The electromechanical clutch actuation provided in some embodiments herein retunes the existing output of the TECU in order to minimize cost and maintain a common TECU for both hydraulic and electromechanical clutch actuation schemes. The VFS output is typically a unipolar, current-controlled Pulse Width Modulation (PWM) drive circuit, and therefore can only drive a bi-directional motor in a single direction. To provide a minimally invasive method for existing TECU architectures to control the bi-directional motor, the control circuits of fig. 9-14 may be provided. Each control circuit or controller may be implemented or realized with a discrete logic system or microcontroller, depending on the requirements of the system.

The TECU may provide power directly to the controller or indirectly control power supplied to the controller. The indirect control approach is advantageous because the current consumption of the controller is not limited by the TECU capabilities. The TECU retains the ability to remove power from the controller.

Referring now to fig. 14, the controller power stage of fig. 14 may be set when it is desired to control the power to the controller even if the controller is not powered directly by the TECU. The controller may be directly connected to the battery power by setting the high-side switch 202, where the TECU may stop the controller's power during a fault and/or when the vehicle is off. The high side switch 202 provides a way to turn off the motor if the MOSFET driven by the PWM command stays in the "on" position.

The TECU provides a high side output that provides the battery voltage to the gate of the N-channel MOSFET. Once an N-channel MOSFET is turned on, the gate of the P-channel MOSFET it is turned on will be grounded. The P-channel MOSFET provides power to the rest of the controller circuit. As an alternative implementation, the high side output of the TECU may directly excite the coil of the n.o. relay. The relay contacts provide power to the rest of the circuit. Fig. 13 is a simplified implementation of a controller with cost advantages. FIG. 13 shows the power signal driving the MOSFET gate (shown as the SPST relay coil). The MOSFET200 then supplies current to the motor.

Still referring to fig. 14, for devices directly connected to the vehicle battery power supply, a protection circuit 204 is provided to prevent damage due to improper installation (i.e., wrong polarity) of the vehicle battery. A simple P-channel MOSFET204 is connected to the circuit before the high-side switch 202. If the battery is connected with the incorrect polarity, the MOSFET204 will have a positive voltage at its gate relative to the drain and will "turn itself off". Under normal conditions, the drain will have a positive battery voltage connected to it, while the gate will have ground potential, causing the MOSFET204 to "turn on".

Fig. 11 and 12 have PWM control signals. Fig. 9 has CAN as a bidirectional communication bus. Any controller concept CAN be implemented using CAN or PWM based communication. The state information and move instructions may be exchanged by implementing a bi-directional communication bus between the TECU and the controller using any number of recognized protocols.

The circuits of fig. 11 and 12 allow the TECU to control the direction and speed of the motor 88, 88', or 88 "that only requires the PWM output of a single TECU. The controller interprets the PWM waveform generated by the TECU and determines the direction of rotation of the motor. In a sense, fig. 11 and 12 have two-way communication (just not on the same bus), the TECU sends the motor current and sensor status through PWM, and the controller communicates the motor current and sensor status back and forth through a combination of analog voltage signals and digital voltage signals. A bidirectional communication bus, in particular a bidirectional communication bus with a CAN system or a LIN system, has the meaning that bidirectional communication takes place on the same physical bus.

A DPDT (double pole double throw) relay may be used in the control circuit if desired, and may be a solid state switch. There are a number of ways to accomplish the switching of the motor leads in the circuit 120: a DPDT relay, a discrete solid state switch, or a full H-bridge module.

The system 80 (as well as the system 80' and the system 80 ") may include a microcontroller (i.e., MCU) containing control logic that may additionally be present in other circuitry in the motor controller of the system 80. Again, the motor controller typically receives command signals from a remote electronic control unit (TECU) across or through an on-board bus.

Fig. 9 also shows a fail-safe power supply circuit for controllably storing power and supplying the stored power to a motor drive Integrated Circuit (IC) or a motor drive circuit 120 based on a fail-safe position command signal in case of a system failure (e.g., communication or power failure) determined by a Microcontroller (MCU). The motor drive IC120 generates a power signal to the drive motor while the TECU maintains the supervisory role. The MCU may be replaced with an FPGA or a very extensive array of discrete modules. The fail safe power circuit may be designed without a low level diagnostic reported to the TECU and may then receive actuation commands from the TECU through a digital output and send information of a high level status (i.e., sensor status or actuation controller failure) back to the TECU through a digital output on the actuation controller. Furthermore, the fail safe actuation circuit may be adapted to any electromechanical actuation scheme in which there is a mechanical lockout.

The MCU or microcontroller receives power and direction command signals from the TECU, typically through the vehicle CAN bus. The MCU also receives various monitoring, control and feedback signals to monitor the various voltages within the power supply circuit to control the motor driver 120 as appropriate. The MCU receives one or more feedback signals from the hall effect sensors and a current feedback signal based on the motor current. The MCU in turn controls the operation of the boost and buck circuits of the power supply circuit and the motor driver 120.

LDO (i.e., low dropout) dc linear regulators regulate the voltage at the output capacitor and provide the regulated voltage to the MCU and the hall effect sensor.

Remote transmission ecus (tecus) typically have a microprocessor, referred to as a Central Processing Unit (CPU), which communicates with a Memory Management Unit (MMU). The MMU controls the movement of data between the various computer-readable storage media and transfers data to and from the CPU. The computer readable storage medium preferably includes volatile and non-volatile storage in Read Only Memory (ROM), Random Access Memory (RAM), and Keep Alive Memory (KAM). For example, the KAM can be used to store various operating variables when the CPU is powered down. The computer readable storage medium may be implemented using any of a number of known storage devices, such as PROMs (programmable read Only memory), EPROMs (electrically PROM), EEPROMs (electrically erasable PROM), flash memory, or any other electrical, magnetic, optical, or combination storage device capable of storing data, some of which represent executable instructions used by the CPU to control the transmission or vehicle in which the transmission is installed.

The computer readable storage medium may also include floppy disks, CD-ROMs, hard disks, etc. The CPU communicates with various sensors, switches, and/or actuators either directly or indirectly through an input/output (I/O) interface, and with actuators either directly or through an input/output (I/O) interface or vehicle bus (i.e., CAN, LIN, etc.). The interface may be implemented as a single integrated interface that provides various raw data or signal conditioning, processing and/or conversion, short circuit protection, and the like. Alternatively, one or more dedicated hardware or firmware chips may be used to condition and process a particular signal before it is provided to the CPU. Some controller architectures do not include an MMU. If the MMU is not used, the CPU will manage the data according to the specific application and connect directly to ROM, RAM and KAM connected to the MMU or CPU.

Depending on the particular application and implementation, the various components or functions of the motor controller of FIG. 9 may be implemented by separate motor controllers as shown, or may be integrated or incorporated into a transmission ECU or other controller. The MCU typically includes control logic for controlling the actuation assembly 82 or 82' or 82 ". The control logic may be implemented in hardware, software, or a combination of hardware and software.

The control logic is also used to determine a system fault and to generate a fail-safe position command or drive signal in the event of a system fault. The actuating assembly 82 or 82 'or 82 "moves the control member 26 or 26' or 26" to a failsafe position based on the failsafe position command signal to prevent inadvertent engagement of the clutch assembly 10. Typically, the control logic determines the desired one of the possible positions of the control member or control panel 26 or 26' or 26 "based on command signals received from a remote electronic control unit over the vehicle bus. The system failure may be an accidental loss of power to the actuation assembly 82 or 82' or 82 ".

The motor controller of fig. 9 typically includes an energy storage device or power circuit (including the storage capacitor and output capacitor of fig. 9 and 10) to controllably store power and provide stored power to the motor drive 120, and then to provide stored power to the dc motor 88 or 88' or 88 "in the event of an accidental loss of power. A system failure may be the MCU losing communication with the remote electronic control unit.

The circuit in fig. 10 includes a backup power circuit or fail-safe power circuit for powering the motor and MCU or microcontroller (through the LDO) in the event of loss of the 12VDC power supply of the vehicle. In normal operation, with 12VDC of the vehicle present, power to the motor and microcontroller will be provided through schottky diode D located on top of the circuit of fig. 10. On the left side of the circuit of fig. 9 is a boost converter or circuit that takes the vehicle's 12VDC supply and boosts it to approximately 40VDC and stores the energy in a storage capacitor. The schottky diode D and a separate diode (not shown) at the input of the boost circuit help to prevent reverse polarity from being provided to the battery. After "firing" and the vehicle's 12 volt DC power supply has stabilized, the microcontroller (i.e., MCU) turns on the booster or converter (at the gate control device) and runs the boost converter until the storage capacitor is charged to 40 VDC. The boost converter will then be turned off and only turned back on when the voltage of the storage capacitor drops below a preprogrammed threshold monitored and determined by the MCU.

On the right side of the power supply circuit is a buck converter or buck circuit that uses a storage capacitor as its input. In the event of a loss of power to the vehicle, the microcontroller (i.e., MCU) will turn on the buck converter (at the gate control device), which will output the necessary outputVoltage (at C)_{Output of}At) to operate the dc motor via the motor driver 120 and to keep the microcontroller on via the LDO for a sufficient time to return the control member to a safe (i.e., failsafe) position or state.

As will be appreciated by those of ordinary skill in the art, one or more memory devices within the transmission ECU and/or motor controller may store a variety of actuation schemes for controlling the components or plates 26 or 26' or 26 ", and may represent any one or more of a number of known processing strategies, e.g., event-driven, interrupt-driven, multi-tasking, multi-threading, etc. As such, various steps or functions may be performed in the sequence, in a modified sequence, in parallel, or in some cases omitted. Likewise, the order of operations or processing is not necessarily required to achieve the objects, features, and advantages of the invention, but is provided for ease of illustration and description.

Although not explicitly illustrated, one of ordinary skill in the art will recognize that one or more of the illustrated steps or functions may be repeatedly performed depending on the particular application and processing strategy being used. Preferably, the control logic is implemented primarily in software executed by a microprocessor-based controller or microcontroller (i.e., MCU). Of course, the control logic may be implemented in software, hardware, or a combination of software and hardware, depending on the particular application. When implemented in software, the control logic is preferably disposed in a computer readable storage medium that stores data representing instructions executed by a computer to control the control member 26 or 26 ' or 26 "of the system 80 or 80 ' or 80" via the actuation assembly 82 or 82 ' or 82 ". The computer-readable storage medium may be any of a number of known physical devices that utilize electrical, magnetic, and/or optical means to store, temporarily or permanently, executable instructions and associated calibration information, operating variables, and the like.

In an exemplary embodiment, the control member or control panel 26, 26 ' or 26 "is electromechanically driven by an actuation assembly that includes a rotary actuator, such as a dc motor 88, 88 ' or 88", and an associated transmission in the form of a lead screw 84, 84 ' or 84 ", or the like. For example, the DC motor 88, 88' or 88 "may be a brushed or brushless DC servo motor, the operation of which is controlled by a motor controller through a motor drive or driver (e.g., an H-bridge motor driver) within the motor controller. The speed and position of the brushed or brushless motor may be controlled by Pulse Width Modulation (PWM) control to adjust the position of the control member or control plate 26, 26', or 26 ".

The motor controller outputs motor drive commands to the motor 88, 88 'or 88 "based on output signals from the hall effect sensor 98, 98' or 98", current feedback from the dc motor, and/or decoded commands from the transmission ECU. The motor controller controls the dc motor via the motor driver 120 of the motor controller, thereby changing the angular position of the control member. In other words, the transmission ECU outputs a servomotor drive command to a motor controller that controls the dc motor 88, 88 'or 88 ″, and controls the selector plate 26, 26' or 26 ″ through its transmission.

The TECU and the motor controller are connected by a vehicle bus, such as a local interconnect network (LIN or CAN) line or bus capable of bidirectional communication. LIN is one of many possible on-board Local Area Network (LAN) communication protocols. The power and ground lines may be disposed between the TECU and the motor controller. The motor controller typically includes a transceiver interface within the MCU, a microprocessor within the MCU and its control logic, a motor drive or driver 120, and a power supply (provided by a fail-safe power supply circuit). The motor controller may be integrated or physically connected with the dc motor 88, 88' or 88 "in the clutch housing, while the TECU is located at a distance from the clutch housing.

The power supply or circuit of the motor controller provides power at a predetermined voltage level to the MCU and the hall effect sensor through the LDO and the motor driver or driver. The transceiver within the MCU is a communication interface circuit connected to a network or vehicle bus for communication and operates as a receiver portion of the MCU and a transmitter portion back to the TECU. The motor driver generally includes a drive circuit for driving a direct current motor.

The hall effect sensor is typically located close to the cam 94, 94 ' or 94 "or connected to or close to the cam 94, 94 ' or 94" (the cam 94, 94 ' or 94 "connects the output shaft of the motor 88, 88 ' or 88" to the selector plate 26, 26 ' or 26 ", respectively) and may be driven synchronously with the rotation of the dc motor to generate a pulse signal that is received by the MCU.

The MCU of the motor controller generally includes a memory and may be configured as a conventional microcomputer including a CPU, ROM, RAM, etc., or as a hard-wired logic circuit.

The TECU and the motor controller may periodically perform data communication via a LIN or CAN bus. In such data communication, the motor controller may send status data to the TECU indicating the state of the dc motor. The status data may comprise the current rotational position of the dc motor, i.e. the count value of a rotational position counter stored in the memory of the MCU of the motor controller.

The TECU and/or the motor controller may confirm the current rotational position of the dc motor. The TECU may then set a target stop position for the dc motor based on the various states detected by the non-contact position sensor commands and the current rotational position of the dc motor, and generate a dc motor drive command to drive the dc motor to one or more target stop positions. Such position sensors provide position feedback signals that vary with the position of the control member or plate 26, 26', or 26 ". Each sensor may include at least one magnetic or ferromagnetic magnet mounted for movement on the cam 94, 94', or 94 "of the actuation assembly and at least one magnetic field sensing element 98, for example, the at least one magnetic field sensing element 98 disposed adjacent to and stationary relative to the at least one magnet in the clutch housing to sense magnetic flux to generate the position feedback signal. Each magnetic field sensing element is preferably a hall effect sensor.

When the logic circuit of the MCU of the motor controller receives a motor drive command from the TECU through its transceiver, it transmits a drive command or signal to the motor drive or driver 120 to rotate the dc motor in forward or reverse direction so that the dc motor stops at a desired target stop position.

If the detected current rotational position of the dc motor reaches the target stop position, that is, the current position coincides with the target stop position, the logic circuit of the MCU transmits a stop instruction to the motor driver to stop the dc motor.

In communication with the TECU, the motor controller may send the current rotational position of the servo motor detected based on the signal of the sensor to the TECU while the dc motor is rotating. The motor controller may also send stop data to the TECU indicating that the dc motor is stopped when the dc motor has stopped at its target stop position. The TECU typically checks whether stop data is included in the data received from the motor controller. If stop data is included, the TECU determines that the DC motor has stopped at the target stop position.

If stop data indicating that the dc motor is stopped is not included, the TECU typically compares the received current rotational position of the dc motor with the current rotational position of the dc motor received in the previous communication to check whether the current rotational position is changed.

In view of the above, at least one embodiment of the system utilizes a bi-directional dc motor, a threaded screw shaft, one or more proximity sensors, a cam having a contoured surface, a motor driver, a microcontroller, and a capacitive energy storage and powering circuit to:

a. actuating the multi-position selectable mechanical diode selector plate and providing a mechanical holding force by a screw shaft (fig. 6) or latching solenoid (fig. 8) or other actuator interface that requires little or no continuous electrical power consumption to be maintained;

b. determining an actual position of the selector plate using one or more proximity sensors (fig. 6);

c. communicating with a user's transmission electronic control unit over a CAN or other vehicle bus to receive actuation instructions and send selector plate position status and system diagnostic data; and

d. an electronic fail-safe is provided that will return the clutch assembly to a safe position or state in the event of a loss of power to the vehicle or a loss of communication with the transmission electronic control unit.

The electrically selectable mechanical diode actuation system of fig. 7 utilizes a mechanical return device (i.e., spring 101') such that the system returns to an initial state in the event of a loss of power to the actuator. In the event of a loss of power to the vehicle, at least one embodiment of the invention returns the selector plate to its original fail-safe position.

In at least one embodiment of the present invention, the proposed mechanism of fig. 6,7 and 8, when connected with a controller such as that of fig. 9 and 12, provides the ability to disengage the clutch when the locking member is loaded. This provides a mechanism that allows the Controllable Mechanical Diode (CMD) to perform a function similar to a conventional clutch pad. Any of the mechanisms of fig. 6,7 or 8 are designed such that forces internal to the clutch cannot change the state of the actuation system. As mentioned above, this is particularly important for cold weather operations.

While exemplary embodiments are described above, these embodiments are not intended to describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Furthermore, features from different embodiments may be combined to form further embodiments of the invention.

Claims (43)

1. An electromechanical system for controlling the operating mode of a selectable clutch assembly, comprising:

a control member mounted for controlled rotation about a first axis;

a bi-directional, electrically driven actuation assembly including an output member connected to a control member for selective, small-displacement angular rotation of the control member about a first axis between different angular positions corresponding to different operating modes of a clutch assembly, the actuation assembly comprising: a rotating output shaft; a threaded screw shaft connected to the output shaft for rotation about a second axis substantially perpendicular to the first axis; and a cam having a contoured surface, the cam being screwed to the screw shaft to move linearly along the second axis upon rotational movement of the screw shaft, the output member riding on the contoured surface of the cam such that the output member rotates about the first axis with the control member;

control logic for determining a desired operating mode of the clutch assembly and generating a corresponding position command signal; and

an actuation controller for controllably supplying electrical power to the actuation assembly to move the control member to a desired angular position based on the position command signal.

2. The electromechanical system for controlling the operational modes of the selectable clutch assembly of claim 1 wherein the actuation controller receives the position command signal from the remote electronic control unit over the bus.

3. The electromechanical system for controlling the operating modes of the selectable clutch assembly of claim 2 wherein the electronic control unit is a transmission electronic control unit of a vehicle and the bus is an on-board bus.

4. The electromechanical system for controlling the operating modes of the selectable clutch assembly of claim 1 wherein the actuation assembly includes a dc motor having an output shaft for driving the control member.

5. The electromechanical system for controlling the operational mode of the selectable clutch assembly of claim 4 wherein the actuation controller includes a current sensor for monitoring a motor current based on which the control logic controls the DC motor.

6. The electromechanical system for controlling the operating mode of the selectable clutch assembly of claim 4 wherein the actuation assembly includes at least one non-contact position sensor for providing a position feedback signal that varies with the position of the cam along the second axis, the control logic controlling the DC motor based on the position feedback signal.

7. The electromechanical system for controlling an operating mode of a selectable clutch assembly as set forth in claim 6 wherein each sensor includes at least one magnetic or ferromagnetic magnet mounted for movement with the cam and at least one magnetic field sensing element disposed adjacent to and stationary relative to said at least one magnet to sense magnetic flux to generate said position feedback signal.

8. The electromechanical system for controlling the operational mode of the selectable clutch assembly of claim 7 wherein each magnetic field sensing element is a Hall effect sensor.

9. The electromechanical system for controlling the modes of operation of the selectable clutch assembly of claim 1 wherein the cam is back drivable on the screw shaft, and wherein the electromechanical system further comprises a return biasing member for applying a biasing force to the cam when the actuating assembly is de-energized to return the cam to a position on the screw shaft corresponding to the safe clutch mode.

10. The electromechanical system for controlling the operational modes of the selectable clutch assembly of claim 1 wherein the cam cannot be back driven on the screw shaft.

11. The electromechanical system for controlling the operational modes of the selectable clutch assembly of claim 9 further comprising a lockout mechanism for preventing the cam from moving linearly on the screw shaft.

12. The electromechanical system for controlling the operational modes of the selectable clutch assembly of claim 11 wherein the lockout mechanism includes a lockout solenoid.

13. The electromechanical system for controlling the operating mode of the selectable clutch assembly of claim 10 wherein the controller includes a boost circuit for storing electrical energy to provide an electrical failsafe for the cam that cannot be back driven.

14. The electromechanical system for controlling the operating modes of the selectable clutch assembly of claim 1 wherein the output member includes an actuating pin or arm connected to the control member.

15. The electromechanical system for controlling the operating mode of the selectable clutch assembly of claim 1 wherein the contoured surface is defined by a groove that receives and retains a free end of the output member therein.

16. The electromechanical system for controlling the operating mode of the selectable clutch assembly of claim 15 wherein the groove has end portions and an intermediate portion between the end portions, the end portions providing an anti-backlash feature.

17. The electromechanical system for controlling the operational modes of the selectable clutch assembly of claim 1 wherein the control member is a control plate or a selector plate rotatable about the first axis.

18. The electromechanical system for controlling the operating modes of the selectable clutch assembly of claim 17 wherein the control member has at least one opening extending completely therethrough.

19. The electromechanical system for controlling the operating mode of the selectable clutch assembly of claim 3 wherein the controller includes a boost circuit for enabling the controller to provide greater power to the actuating assembly than a rated input power normally available from a battery of the vehicle to increase the output torque and speed of the actuating assembly.

20. The electromechanical system for controlling the operating mode of the selectable clutch assembly of claim 19 wherein the cam is not capable of back driving and wherein the boost circuit stores electrical energy to provide an electrical failsafe for the cam.

21. An override connection and electromechanical control assembly comprising:

a connection subassembly including first and second connection members each having first and second connection faces closely opposed to each other, at least one of the first and second connection members being mounted for rotation about a first axis;

a control member mounted for controlled rotation about a first axis between the first and second connection faces;

a bi-directional, electrically driven actuation subassembly including an output member connected to a control member for selective, small-displacement angular rotation of the control member about a first axis between different angular positions corresponding to different operating modes of the connection subassembly, the actuation subassembly comprising: a rotating output shaft; a threaded screw shaft connected to the output shaft for rotation about a second axis substantially perpendicular to the first axis; and a cam having a contoured surface, the cam being screwed to the screw shaft to move linearly along the second axis upon rotational movement of the screw shaft, the output member riding on the contoured surface of the cam such that the output member rotates about the first axis with the control member;

control logic for determining a desired mode of operation of the connection subassembly and generating a corresponding position command signal; and

an actuation controller for controllably supplying electrical power to the actuation subassembly to move the control member to a desired angular position based on the position command signal.

22. The override connection and electromechanical control assembly according to claim 21, wherein the actuation controller receives the position command signal from the remote electronic control unit via the bus.

23. The override connection and electromechanical control assembly according to claim 22, wherein the electronic control unit is a transmission electronic control unit of a vehicle and the bus is an onboard bus.

24. The override connection and electromechanical control assembly according to claim 21, wherein the actuation subassembly includes a dc motor having an output shaft for driving the control member.

25. The override connection and electromechanical control assembly according to claim 24, wherein the actuation controller includes a current sensor for monitoring a motor current based on which the control logic controls the dc motor.

26. The override connection and electromechanical control assembly according to claim 24, wherein the actuation subassembly includes at least one non-contact position sensor for providing a position feedback signal that varies with a position of the cam along the second axis, the control logic controlling the dc motor based on the position feedback signal.

27. The override connection and electromechanical control assembly according to claim 26, wherein each sensor includes at least one magnetic or ferromagnetic magnet mounted for movement with the cam, and at least one magnetic field sensing element disposed adjacent to and stationary relative to the at least one magnet to sense magnetic flux to generate the position feedback signal.

28. The override connection and electromechanical control assembly according to claim 27, wherein each magnetic field sensing element is a hall effect sensor.

29. The override connection and electromechanical control assembly according to claim 21, wherein the cam is back-drivable on the screw shaft, and wherein the override connection and electromechanical control assembly further comprises a return biasing member for applying a biasing force to the cam when the actuation subassembly is de-energized to return the cam to a position on the screw shaft corresponding to the safe connection mode.

30. The override connection and electromechanical control assembly according to claim 21, wherein the cam cannot be back driven on the screw shaft.

31. The override connection and electromechanical control assembly according to claim 30, wherein the controller includes a boost circuit for storing electrical energy to provide an electrical failsafe for the non-back drivable cam.

32. The override connection and electromechanical control assembly according to claim 29, further comprising a latching mechanism for preventing the cam from moving linearly on the screw shaft.

33. The override connection and electromechanical control assembly according to claim 32, wherein the latching mechanism comprises a latching solenoid.

34. The override connection and electromechanical control assembly according to claim 21, wherein the output member includes an actuating pin or arm connected to the control member.

35. The override connection and electromechanical control assembly according to claim 21, wherein the contoured surface is defined by a groove that receives and retains a free end of the output member therein.

36. The override connection and electromechanical control assembly according to claim 35, wherein the groove has end portions and an intermediate portion therebetween, the end portions providing an anti-backlash feature.

37. The override connection and electromechanical control assembly according to claim 21, wherein the control member is a control or selector plate rotatable about the first axis.

38. The override connection and electromechanical control assembly according to claim 21, further comprising a locking member disposed between the first and second connection faces of the connection member, the locking member being movable between a first position and a second position, the control member being operable to control the position of the locking member.

39. The override connection and electromechanical control assembly according to claim 38, wherein the locking member is a counter strut.

40. The override connection and electromechanical control assembly according to claim 37 wherein the control member has at least one opening extending completely therethrough for allowing the locking member to extend through the opening to the first position of the locking member in the control position of the control member.

41. The override connection and electromechanical control assembly according to claim 23, wherein the controller includes a boost circuit for enabling the controller to provide greater power to the actuation subassembly than a rated input power typically available from a battery of the vehicle to increase an output torque and speed of the actuation subassembly.

42. The override connection and electromechanical control assembly according to claim 41, wherein the cam is not back drivable, and wherein the boost circuit stores electrical energy to provide an electrical failsafe for the cam.

43. The override connection and electromechanical control assembly according to claim 21, wherein one of the connection members comprises a notch plate and the other of the connection members comprises a slot plate.

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